1. Field of the Invention
The present invention relates to a process for the preparation of esters, more particularly, a process for the preparation of esters having a large steric hindrance. According to the present invention, the target esters can be easily and effectively prepared. The present invention also relates to a process for the preparation of a chemically amplified resist material comprising an alicyclic hydrocarbon group-containing polymer, which comprises polymerizing esters after they were prepared in accordance with the preparation process of the present invention. As will be appreciated from the descriptions of this specification, the term "polymer" used herein is intended to mean both a homopolymer and a copolymer which is produced by the simultaneous polymerization of two, three or more dissimilar monomeric compounds or monomers. The chemically amplified resist material can exhibit a high resolution, a high sensitivity and an excellent resistance to dry etching. The resist composition of the present invention can exhibit a high sensitivity and stable patterning properties which are particularly desired in the field of KrF and ArF lithography. In addition, the present invention relates to a process for the production of a semiconductor devices such as semiconductor integrated circuits, for example, LSIs, VLSIs, ULSIs and other devices, using the chemically amplified resist material of the present invention in a lithographic process.
2. Description of the Related Art
Recently, in the field of the production of semiconductor devices, to satisfy the requirements for the formation of fine resist patterns, attention has been made to a chemically amplified resist material and lithographic process using such material. At present, a wide variety of chemically amplified resist materials are well known.
For example, as is disclosed in Japanese Unexamined Patent Publication (Kokai) No. 4-39665, the inventor of the present application has invented a chemically amplified resist material characterized by comprising a polymer or copolymer of acrylic acid ester or a-substituted acrylic acid ester in which the ester portion contains an adamantane skeleton. The chemically amplified resist material can be effectively used in the formation of submicron-ordered resist patterns using as a patterning radiation the radiation in the range of far ultraviolet or vacuum ultraviolet lights, because they have an excellent transparency to the patterning radiation and also a high resistance to dry etching.
The resist polymers or copolymers containing the above-described ester structure are generally produced by reacting an alcohol containing the part corresponding to said ester structure with an acid or acid halide, that is, using conventional esterification methods, to produce an ester, followed by conducting a polymerization reaction using the ester as a starting monomer. However, the production process has a drawback in that, using the conventional methods, it is difficult to easily, effectively and stably carry out the preparation of the ester. For example, the previous preparation of an alcohol as the starting material is troublesome. Further, if the esterification of a tertiary alcohol is carried out to obtain a target ester, a dissociation reaction may be caused in the resulting ester due to the presence of stable carbocations, and an esterification reaction itself is inhibited due to the steric hindrance of the contained substituents.